Lentigo maligna: a comprehensive review on diagnosis and treatment.

Lentigo maligna (LM), a form of melanoma in situ, and LM melanoma (LMM), its invasive counterpart, exhibit distinctive epidemiology, risk factors, and clinical features compared to other melanoma subtypes. Notably, LM occurs on chronically sun-damaged skin presenting as a slow-growing, ill-defined patch which makes it difficult to diagnose and to treat. Additionally, while LM generally presents a favourable prognosis, it can also lead to dermal invasion and behave similarly to other melanomas with the same Breslow thickness. Hence, surgery continues to be the cornerstone treatment. Wide excisions are often necessary, but challenges arise when these lesions manifest in cosmetically sensitive regions, limiting the feasibility and desirability of large excisions. Specialized approaches, including margin-controlled surgery and image-guided treatment with reflectance confocal microscopy, have been developed to address these issues. Other non-surgical treatments such as cryosurgery, imiquimod, radiotherapy, or photodynamic therapy, may also be used but commonly present with recurrent/persistent disease. Herein we comprehensively review the existing literature on the management of LM/LMM, and discus the potential new advances on managing this challenging skin cancer.

Extrafacial lentigo maligna: A progression model and enhanced diagnostic techniques using dermatoscopy and reflectance confocal microscopy.

Lentigo maligna (LM) is a subtype of lentiginous melanoma confined to the epidermis, which is associated with chronic sun exposure. Its clinical, dermatoscopic, and histopathological diagnosis can be challenging, particularly in the early and advanced stages, requiring appropriate clinicopathological correlation. This article reviews the clinical presentation, diagnosis through noninvasive methods (dermoscopy and confocal microscopy), and provides insights for diagnosis of extrafacial LM through the presentation of four representative clinical cases from different phases of a theoretical-practical progression model. Recognizing these lesions is crucial, as once they invade the dermis, they can behave like any other type of melanoma.

Melanocyte Density in the Diagnosis of Melanoma In Situ in Sun-Damaged Skin.

ABSTRACT: Histologic differentiation between melanoma in situ in chronically sun-damaged skin (CSDS) [lentigo maligna (LM)] and CSDS without malignancy is difficult because signs of melanocyte activation and proliferation are found in both. A potentially reliable and quantifiable criterion is melanocyte density (MD). Here, we evaluated whether and to what extent MD allows the distinction between LM and CSDS, which is particularly relevant for the evaluation of borderline cases and surgical margins.Articles assessing MD in LM and/or CSDS were evaluated in a systematic review. The results were categorized and compared according to staining. Cutoff values were included whenever stated.Twenty articles matched the selection criteria. Six hundred forty-four samples of CSDS and 227 samples of LM were considered. In each individual study, mean MD scores were higher for LM than for CSDS. However, looking at the overall study situation, it becomes clear that the data are very heterogeneous and show overlaps. Therefore, no reliable orientation value can be derived. Only 1 article defined a cutoff value.The data of MD in LM in contrast to CSDS were sparse, and a defined cutoff value was only mentioned in 1 article for microphthalmia-associated transcription factor, which cannot yet be generalized. Especially regarding the importance for the definition of surgical resection margins, this unsatisfactory data set highlights the need for further studies. More precise diagnostic criteria could spare some patients extensive and possibly disfiguring surgery.

The combination of dermoscopy and reflectance confocal microscopy increases the diagnostic confidence of amelanotic/hypomelanotic lentigo maligna.

The dermoscopic diagnosis of amelanotic/hypomelanotic lentigo maligna/lentigo maligna melanoma (AHLM/LMM) may be very difficult in its early stages because of lack of pigment. Reflectance confocal microscopy (RCM) is an imaging technique that is especially helpful for the diagnosis of lentigo maligna. To determine the diagnostic performances of dermoscopy and RCM in the diagnosis of AHLM/LMMs we evaluated dermoscopic and RCM images of consecutive cases of histopathologically confirmed AHLM/LMMs, amelanotic/hypomelanotic basal cell carcinoma and squamous cell carcinoma (AHBCCs/AHSCCs), amelanotic/hypomelanotic benign lesions (AHBLs), and actinic keratoses (AKs) from five participating centers. Sensitivity, specificity, accuracy, predictive values, and level of diagnosis confidence were calculated for both diagnostic procedures. Both dermoscopy and RCM showed diagnostic performance >97% in the diagnosis of AHLM/LMMs versus AHBCC/AHSCCs and their combination slightly improved diagnostic performance, with accuracy increasing from 98.0% to 99.1%. Similarly, RCM in combination with dermoscopy showed a tiny increase in the diagnostic performance in the diagnosis of AHLM/LMMs versus AHBLs (accuracy increased from 87.2% to 88.8%) and versus AKs (accuracy increased from 91.4% to 93.4%). Although the increase in diagnostic performance due to RCM was modest, the combination of dermoscopy and RCM greatly increased the level of confidence; high confidence in the diagnosis of AHLM/LMMs versus AHBLs increased from 36.2% with dermoscopy alone to 76.6% with dermoscopy plus RMC. Based on our results, dermoscopy and RCM should be complementary to improve not only diagnostic accuracy but also the level of diagnostic certainty in the diagnosis of AHLM/LMMs.

Lentigo maligna: a review.

Lentigo maligna (LM) is a melanoma in situ with distinct clinical features and histology. It commonly affects men after the sixth decade of life. Incidence rates of LM have increased based on early 21st century data from different countries; however, data are suboptimal. Data from England show a plateauing crude incidence between 2013 and 2019. By comparison, invasive melanoma and other types of melanoma in situ commonly appears in younger age groups (median age 58 and 67 years old, respectively) and incidence is rising. The most important risk factors for LM include fair skin and cumulative ultraviolet solar radiation exposure. Although LM is limited to the epidermis and connected skin adnexa, it may progress to invasive LM melanoma. The reported rate of malignant progression varies, reflecting a challenge for LM epidemiology research as often lesions are removed on diagnosis. LM poses a challenge in diagnosis and management. Although it can be diagnosed clinically or dermoscopically, histopathological assessment of biopsied skin tissue remains the gold standard. Reflectance confocal microscopy allows for better appreciation of the complexity of LM at a cellular level, often progressing beyond clinical margins. Management of LM may involve Mohs micrographic surgery or excision, although recurrence may occur even with 5 mm clinical margins. Imiquimod cream may be effective, but incomplete treatment and recurrence has been reported. Conservative management with observation or radiotherapy may be used in selected patients' cases. Five-year net survival rates are excellent. This paper reviews the natural history, epidemiology, aetiology, pathogenesis, diagnosis and management of LM.

A risk-scoring model for the differential diagnosis of lentigo maligna and other atypical pigmented facial lesions of the face: The facial iDScore.

BACKGROUND: Due to progressive ageing of the population, the incidence of facial lentigo maligna (LM) of the face is increasing. Many benign simulators of LM and LMM, known as atypical pigmented facial lesions (aPFLs-pigmented actinic keratosis, solar lentigo, seborrheic keratosis, seborrheic-lichenoid keratosis, atypical nevus) may be found on photodamaged skin. This generates many diagnostic issues and increases the number of biopsies, with a subsequent impact on aesthetic outcome and health insurance costs. OBJECTIVES: Our aim was to develop a risk-scoring classifier-based algorithm to estimate the probability of an aPFL being malignant. A second aim was to compare its diagnostic accuracy with that of dermoscopists so as to define the advantages of using the model in patient management. MATERIALS AND METHODS: A total of 154 dermatologists analysed 1111 aPFLs and their management in a teledermatology setting: They performed pattern analysis, gave an intuitive clinical diagnosis and proposed lesion management options (follow-up/reflectance confocal microscopy/biopsy). Each case was composed of a dermoscopic and/or clinical picture plus metadata (histology, age, sex, location, diameter). The risk-scoring classifier was developed and tested on this dataset and then validated on 86 additional aPFLs. RESULTS: The facial Integrated Dermoscopic Score (iDScore) model consisted of seven dermoscopic variables and three objective parameters (diameter ≥ 8 mm, age ≥ 70 years, male sex); the score ranged from 0 to 16. In the testing set, the facial iDScore-aided diagnosis was more accurate (AUC = 0.79 [IC 95% 0.757-0.843]) than the intuitive diagnosis proposed by dermatologists (average of 43.5%). In the management study, the score model reduced the number of benign lesions sent for biopsies by 41.5% and increased the number of LM/LMM cases sent for reflectance confocal microscopy or biopsy instead of follow-up by 66%. CONCLUSIONS: The facial iDScore can be proposed as a feasible tool for managing patients with aPFLs.

Lentigo maligna and lentigo maligna melanoma in vivo differentiation with dermoscopy and reflectance confocal microscopy: A retrospective, multicentre study.

INTRODUCTION: Dermoscopic predictors of lentigo maligna (LM) and lentigo maligna melanoma (LMM) have been recently reported, but these have not been reported in reflectance confocal microscopy (RCM). OBJECTIVES: (i) To validate dermoscopic predictors for LM/LMM, (ii) to identify RCM patterns in LM and LMM, and (iii) correlations between dermoscopic and RCM features in LM and LMM. MATERIALS AND METHODS: A retrospective, multicentre study of consecutive lesions with histologically proven LM or LMM subtypes of the head and face, with complete sets of dermoscopic and RCM images. RESULTS: A total of 180 lesions were included (n = 40 LMM). Previously reported differential dermoscopic features for LM subtypes were confirmed. Other features significantly associated with LMM diagnosis included irregular hyperpigmented areas, shiny white streaks, atypical vessels and light brown colour at dermoscopy and medusa head-like structures, dermal nests and nucleated cells within the papillae at RCM (p < 0.05). Correlations among LM lesions between dermoscopic and RCM features included brown to-grey dots and atypical cells (epidermis), grey colour and inflammation and obliterated follicles and medusa head-like structures. Among LMM lesions, significant correlations included obliterated follicles with folliculotropism, both irregular hyperpigmented areas and irregular blotches with widespread atypical cell distribution (epidermis), dermal nests and nucleated cells within the papillae (dermis). Irregular blotches were also associated with medusa head-like structures (dermal epidermal junction [DEJ]). CONCLUSIONS: Dermoscopic and RCM features can assist in the in vivo identification of LM and LMM and many are correlated. RCM three-dimensional analysis of skin layers allows the identification of invasive components in the DEJ and dermis.

El lentigo maligno: actualización y claves en el diagnóstico y el tratamiento / Update on Lentigo Maligna: Diagnostic Signs and Treatment

El lentigo maligno es un melanoma cutáneo in situ que asienta en zonas con daño solar acumulado. Su presentación más habitual es como una mancha irregularmente pigmentada de crecimiento lento y progresivo localizada en la cara de un paciente añoso. Aunque el porcentaje real de casos de lentigo maligno que evoluciona a formas invasoras es desconocido, se calcula que supone entre un 2 y un 5% de los casos. Tanto el diagnóstico clínico como histopatológico del lentigo maligno puede suponer un reto, especialmente en casos precoces o atípicos. Su tratamiento también puede suponer un desafío por su localización en áreas muy visibles y por su tamaño frecuentemente considerable, lo que tiene implicaciones estéticas y ocasionalmente también funcionales derivadas de la cirugía. En este trabajo revisamos las claves clínicas e histopatológicas para facilitar el diagnóstico del lentigo maligno. También revisamos las opciones de tratamiento con especial atención a la cirugía (AU)

Lentigo maligna is an in situ cutaneous melanoma that arises in sun-damaged skin. Its most common presentation is a progressive, slow-growing, irregularly pigmented spot on the face of older patients. Although the exact percentage of Lentigo maligna that progresses to invasive tumors is unknown, it is thought to lie between 2% and 5%. Both the clinical and histologic diagnosis of Lentigo maligna can be challenging, especially in patients with early-stage or atypical disease. Treatment also holds challenges, because lesions are located in highly visible areas and are often large. Surgery can thus compromise cosmetic and sometimes functional outcomes. We review clinical and histopathological findings that can facilitate the diagnosis of Lentigo maligna. We also examine treatment options, with a focus on surgery (AU)

[Translated article] Update on Lentigo Maligna: Diagnostic Signs and Treatment / El lentigo maligno: actualización y claves en el diagnóstico y el tratamiento

Lentigo maligna is an in situ cutaneous melanoma that arises in sun-damaged skin. Its most common presentation is a progressive, slow-growing, irregularly pigmented spot on the face of older patients. Although the exact percentage of Lentigo maligna that progresses to invasive tumors is unknown, it is thought to lie between 2% and 5%. Both the clinical and histologic diagnosis of Lentigo maligna can be challenging, especially in patients with early-stage or atypical disease. Treatment also holds challenges, because lesions are located in highly visible areas and are often large. Surgery can thus compromise cosmetic and sometimes functional outcomes. We review clinical and histopathological findings that can facilitate the diagnosis of Lentigo maligna. We also examine treatment options, with a focus on surgery (AU)

El lentigo maligno es un melanoma cutáneo in situ que asienta en zonas con daño solar acumulado. Su presentación más habitual es como una mancha irregularmente pigmentada de crecimiento lento y progresivo localizada en la cara de un paciente añoso. Aunque el porcentaje real de casos de lentigo maligno que evoluciona a formas invasoras es desconocido, se calcula que supone entre un 2 y un 5% de los casos. Tanto el diagnóstico clínico como histopatológico del lentigo maligno puede suponer un reto, especialmente en casos precoces o atípicos. Su tratamiento también puede suponer un desafío por su localización en áreas muy visibles y por su tamaño frecuentemente considerable, lo que tiene implicaciones estéticas y ocasionalmente también funcionales derivadas de la cirugía. En este trabajo revisamos las claves clínicas e histopatológicas para facilitar el diagnóstico del lentigo maligno. También revisamos las opciones de tratamiento con especial atención a la cirugía (AU)

Update on Lentigo Maligna: Diagnostic Signs and Treatment. / El lentigo maligno: actualización y claves en el diagnóstico y el tratamiento.

Lentigo maligna is an in situ cutaneous melanoma that arises in sun-damaged skin. Its most common presentation is a progressive, slow-growing, irregularly pigmented spot on the face of older patients. Although the exact percentage of Lentigo maligna that progresses to invasive tumors is unknown, it is thought to lie between 2% and 5%. Both the clinical and histologic diagnosis of Lentigo maligna can be challenging, especially in patients with early-stage or atypical disease. Treatment also holds challenges, because lesions are located in highly visible areas and are often large. Surgery can thus compromise cosmetic and sometimes functional outcomes. We review clinical and histopathological findings that can facilitate the diagnosis of Lentigo maligna. We also examine treatment options, with a focus on surgery.

In vivo reflectance confocal microscopy can detect the invasive component of lentigo maligna melanoma: Prospective analysis and case-control study.

BACKGROUND: Lentigo maligna (LM), a form of melanoma in situ, has no risk of causing metastasis unless dermal invasive melanoma (LMM) supervenes. Furthermore, the detection of invasion impacts prognosis and management. OBJECTIVE: To assess the accuracy of RCM for the detection of invasion component on LM/LMM lesions. METHODS: In the initial case-control study, the performance of one expert in detecting LMM at the time of initial RCM assessment of LM/LMM lesions was recorded prospectively (n = 229). The cases were assessed on RCM-histopathology correlation sessions and a panel with nine RCM features was proposed to identify LMM, which was subsequently tested in a subset of initial cohort (n = 93) in the matched case-control study by two blinded observers. Univariable and multivariable logistic regression models were performed to evaluate RCM features predictive of LMM. Reproducibility of assessment of the nine RCM features was also evaluated. RESULTS: A total of 229 LM/LMM cases evaluated by histopathology were assessed blindly and prospectively by an expert confocalist. On histopathology, 210 were LM and 19 were LMM cases. Correct identification of an invasive component was achieved for 17 of 19 LMM cases (89%) and the absence of a dermal component was correctly diagnosed in 190 of 210 LM cases (90%). In the matched case-control (LMM n = 35, LM n = 58), epidermal and junctional disarray, large size of melanocytes and nests of melanocytes were independent predictors of LMM on multivariate analysis. The interobserver analysis demonstrated that these three features had a fair reproducibility between the two investigators (K = 0.4). The multivariable model including those three features showed a high predictive performance AUC = 74% (CI 95% 64-85%), with sensitivity of 63% (95% CI 52-78%) and specificity of 79% (CI 95% 74-88%), and likelihood ratio of 18 (p-value 0.0026). CONCLUSION: Three RCM features were predictive for identifying invasive melanoma in the background of LM.

Line-field confocal optical coherence tomography of lentigo maligna with horizontal and vertical histopathologic correlations.

Lentigo maligna (LM) is a subtype of in situ melanoma that classically presents in elderly patients as a slowly growing lesion on sun-exposed areas that may evolve to invasive melanoma. Line-field confocal optical coherence tomography (LC-OCT) is a new non-invasive technique for a real-time, vertical, and horizontal skin imaging with high resolution close to conventional histopathology. We present the LC-OCT features of an LM of the nose in a 49-year-old white man along with their horizontal and vertical histopathological correlations. LC-OCT was able to detect in vivo, in both horizontal and vertical imaging, the main microscopic features typical of LM by showing, in the epidermis and around the hair follicles, the presence of large, bright roundish, or dendritic atypical cells, with evident nuclei, corresponding to atypical melanocytes with a tendency toward folliculotropism. A strong correspondence between LC-OCT images and vertical and horizontal histopathological sections was observed. Our study, although limited to a single case, is indicative of the great potential of LC-OCT to improve the non-invasive diagnosis of LM.

Reflectance confocal microscopy of facial neoplasms: Follicular involvement as a clue to diagnosis.

BACKGROUND: Facial skin is characterized by high density of follicles. Facial neoplasms may present overlapping clinical and dermoscopic findings. Our goal was to evaluate and compare, via reflectance confocal microscopy (RCM), follicular involvement in facial neoplasms. METHODS: We retrospectively searched our image database, between January 2008 and December 2020, for all facial lesions with (1) a standardized set of clinical, dermoscopic, and RCM images, and (2) a biopsy-proven diagnosis of lentigo maligna/lentigo maligna melanoma (LM/LMM, n = 39), basal cell carcinoma (BCC, n = 51), squamous cell carcinoma in situ (SCCIS, n = 5), actinic keratosis (AK, n = 11), and lichen-planus-like keratosis (LPLK, n = 18). Two readers jointly evaluated the RCM images for a set of predefined features of follicular involvement. RESULTS: Diffuse obliteration of follicles was frequent in BCC (88%), while follicular infiltration by refractile dendritic cells and/or by bright round nucleated cells was common in melanoma (90% and 44%, respectively). Extension of atypical keratinocytes down follicles was more prominent among SCCIS than AK (80% vs. 45%, p = 0.01). In most LPLK (89%), there was follicular sparing. CONCLUSIONS: Evaluation of RCM criteria centering on the follicles can be useful in the differential diagnosis between common facial neoplasms.

Immunostained Frozen Sections Vs Traditional Permanent Paraffin Sections for Lentigo Maligna Treated With Mohs Micrographic Surgery.

BACKGROUND: Mohs micrographic surgery (MMS) has risen in popularity as a management option for treating lentigo maligna (LM) because of its ability to accurately detect subclinical spread while conserving tissue. The primary concern for opponents of MMS in melanoma remains the difficulty associated with interpretation of frozen sections compared with traditional paraffin sections; this has been made easier with the advent of immunostaining. OBJECTIVE: Our study aims to assess the concordance in clearance reporting of LM in immunostained frozen sections compared with permanent paraffin sections and hematoxylin and eosin staining. METHODS: We conducted a retrospective analysis of 38 LM cases treated by MMS between 2017 and 2020 in Melbourne, Australia. Immunostained frozen sections were assessed by a Mohs surgeon, whereas permanent paraffin sections were assessed by an external dermatopathologist. RESULTS: We report 86% agreement in reporting of LM in immunostained frozen sections compared with permanent paraffin sections. In 5/38 cases, permanent paraffin sections were reported as clear for LM, but the Mohs surgeon had detected positive margins, requiring further excision. CONCLUSION: For LM treated with MMS, there is a high agreement of clearance reporting between immunostained stained frozen sections and permanent paraffin sections without immunostaining; however, immunostained frozen sections may be more sensitive.

Fluorescence-advanced videodermatoscopy (FAV) for the differential diagnosis of suspicious facial lesions: A single-centre experience with pattern analysis and histopathological correlation.

BACKGROUND: Fluorescence-advanced videodermatoscopy (FAV) is a new non-invasive high-resolution skin imaging technique to assess pigmented lesions in conjunction with the clinical examination and dermatoscopy. OBJECTIVES: This is the first prospective study to identify morphologic descriptors and standardized terminology to examine facial pigmented lesions using FAV. The objectives were to identify FAV indicators, which can assist physicians in diagnosing suspicious flat facial pigmented lesions. METHODS: Consecutive equivocal pigmented lesions were retrospective analysed. Histopathological examination was performed for all the lesions. The main cytomorphological and cytoarchitectural FAV features were described and correlated with histopathological characteristics. RESULTS: From January to October 2020, 21 consecutive clinically suspected pigmented lesions in 20 patients were analysed using dermatoscopy and FAV and then surgically excised. Histopathological examination identified lentigo maligna (LM), lentigo maligna melanoma (LMM), solar lentigo (SL), flat seborrheic keratosis (SK) and pigmented actinic keratosis (PAK). Thirteen malignant melanocytic lesions were removed (11 LM, 2 LMM), two were diagnosed as PAK, and the remaining six pigmented lesions were SL-SKs. With FAV, large ovoid pleomorphic and dendritic cells arranged in the intrafollicular disposition, are typical of most malignant melanocytic lesions (12/13, 92.3%). No benign lesions displayed these features. In dermatoscopy, this folliculotropism corresponded to the presence of an annular-granular pattern with slate grey dots that were aggregated asymmetrically around follicular openings. CONCLUSIONS: FAV features can provide an improved diagnostic approach in the differential diagnosis of flat pigmented facial lesions.

Recurrent lentigo maligna in a young patient.

Lentigo maligna (LM) is usually diagnosed in sun-damaged skin of elderly patients and a correct excision of the lesion determines a complete healing from the disease. LM is very rare in young patients and, for this reason, it can be commonly misdiagnosed. We describe the case of a locally recurrent LM in a 19-year-old male patient, which initially arose at the age of 17 years. In order to avoid diagnostic pitfalls, clinicians have to put more emphasis on diseases which previously were prerogative only of elderly patients and that now could begin to engage a younger age, according to climate and behavior changes.